The long-term goal of the training program is to provide the applicant with solid theoretical and technical foundations for independent research in developmental physiology, especially as it pertains to the development of the visual system in man. Formal training in Phase I will consist of coursework and seminar series in developmental neurobiology. This will be supplemented by supervised hands-on experience in the application of visual evoked potentials. (VEPs), forced-choice preferential looking (FPL), and electroretinography (ERG) to the human infant. The premature infant is at high risk for abnormal visual development, and previous studies have suggested that the high light levels of the neonatal ICU may contribute to this increases risk. The research plan in Phase I will consist of (1) a pilot phase in which normative values for monocular, multi-electrode sweep VEP acuities are established, and (2) a prospective, randomized, longitudinal study of premature infants exposed to (i) continuous bright lighting (the usual NICU environment), (ii) continuous but reduced lighting, (iii) diurnally-cycled bright lighting and darkness, (iv) diurnally-cycled reduced lighting and darkness. Visual function will be assessed by sweep-VEP acuity measurements. In Phase II, the goals will be to further define the effects of prematurity on the developing visual system. Scotopic and photopic ERGs will be used to assess the integrity of the receptors. Modifications of the sweep-VEP technique will be used to assess contrast sensitivity and the integrity of the on- and off- pathways. A steady-state VEP technique will measure the development of orientation tuning. The FPL technique will provide a behavioral estimate of visual function. The planned research will provide a more detailed understanding of early visual system development in man. In addition, the study may point to a practical means of reducing damage to the immature nervous system induced by the environment of the neonatal ICU.